From owner-freebsd-bugs@freebsd.org Fri Apr 26 08:31:01 2019 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id CE5C6158CE57 for ; Fri, 26 Apr 2019 08:31:00 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 4EC7088F11 for ; Fri, 26 Apr 2019 08:31:00 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id 0F9E5158CE56; Fri, 26 Apr 2019 08:31:00 +0000 (UTC) Delivered-To: bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id F07A5158CE54 for ; Fri, 26 Apr 2019 08:30:59 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.ysv.freebsd.org (mxrelay.ysv.freebsd.org [IPv6:2001:1900:2254:206a::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 8391088F0D for ; Fri, 26 Apr 2019 08:30:59 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.ysv.freebsd.org (Postfix) with ESMTPS id D2C2F116A3 for ; Fri, 26 Apr 2019 08:30:58 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id x3Q8UwZx062742 for ; Fri, 26 Apr 2019 08:30:58 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id x3Q8UwsH062741 for bugs@FreeBSD.org; Fri, 26 Apr 2019 08:30:58 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 237576] UART NS8250 parity and frame errors detection doesn't work Date: Fri, 26 Apr 2019 08:30:58 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: smaryus@gmail.com X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Apr 2019 08:31:01 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D237576 Bug ID: 237576 Summary: UART NS8250 parity and frame errors detection doesn't work Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: smaryus@gmail.com On the UART NS8250 errors (parity/frame) are not detected when data is rece= ived because every time there is a read on LSR register the errors bit is remove= d. See [1] Current UART core implementation relies on the LSR register to detect if da= ta is received. If data is received LSR is read again in pair with DATA regist= er to determine if the received byte generate any errors. At this time LSR err= or bit is clear so no errors are reported. In code: 1. uart_core.c: `uart_intr()` calls `UART_IPEND` which will go into `ns8250_bus_ipend()`. Here LSR register is read and returns data received. 2. `uart_intr` calls `uart_intr_rxready` -> `UART_RECEIVE` -> `ns8250_bus_receive`. Here LSR is read again to check if the received byte generated error, but error bit from LSR is now 0. It was cleared by step 1. [1] https://en.wikibooks.org/wiki/Serial_Programming/8250_UART_Programming#Line= _Status_Register --=20 You are receiving this mail because: You are the assignee for the bug.=